Henry



one armor "mm UNITED STATES PATENT OFFICE.

v GEORGE WVASHIN GTON HENRY, OF CHEROKEE, IOWA, ASSIGNOR OF ONE HALF TO RODNEY L. ROBIE, OF SAME PLACE.

COMPOSlTiON BLACKBOARD.

SPECIFICATION forming part of Letters Patent NO. 453,388, dated B11162, 1891. Application filed October 14, 1890. Serial No. 368,087. (No specimens To all whom it may concern: dients can also be ut n in compact form for 30 Be it known that I, GEORGE WAsHINcToN shioinent to place use, VlZZ entrancing" HENRY, a citizen of the United States, residlam 51761;, emerv-dust, marb ust, an ing at Cherokee, in the county of Cherokee iiiacic aniimonv, and the boar sconi letedby and State of Iowa, have invented a new and the addition of the other ma eria sa'ifThd -usez' ulI-rnpeevc1nent-i-n Cempcsition "Blaekplacefif'mmg. 33 boards for Use in Schools, &c.,of which the 1S- oar combines ease of manufacture,

following is aspecification. durability far exceeding that of boards in My composition consists of the following common use, readiness of cleaning, and perro ingredients, combined in the proportions fectadaptation to its intended use. It prestated, viz: fine sand. twenty pounds; stucco, sents a smooth compact surface and one upon 0 fifteen pounds; slalzed li e, (putty,$ live which the chalk or crayon readily takes hold pounds; Portland cement, one pound; lam and upon which the marks are easily seen.

hail

, black, one poun 5 ac antimon one Having thus described my inventiomwhat pound; marble-dust, one pound; emery-(lust, I claim as new 1sf one ounce; white ue, one ounce; plnstering- 1. The herein-described composition of ma- 5 hair, one ounce; water suflicien to mix. terials, consisting of sand, stucco, slakedlime, ese materials, sniiahly mixed, are applied cement, lamp-black, hair, black antimony, to any surface where a blackboard is desired, glue, marble-dust, emery-dust, and water, in similarly to ordinary plastering, being usually the proportions stated, for useas a blackboard,

put, however, upon a suitable backing of with or without the backing, substantially as 50 about one-half-inch thickness of plastering above. composed of four parts of sand to one part of 2. The completed boards, made atafactory stucco, sufificient to make a solid back for the or other place and set up where required, blackboard finish; or the complete boards substantially as above set forth.

maybe made in sections of any desired shape GEORGE WASHINGTON HENRY. or size and attached to the walls by screws or Witnesses: other suitable fastenings. A. R. MOLYNEUX,

The following-mentioned of above ingre- R. L. ROBIE. 

